Method of producing catalyst for synthesis of unsaturated aldehyde and unsaturated carboxylic acid and catalyst prepared by this method

ABSTRACT

The method of producing a catalyst for synthesis of an unsaturated aldehyde and unsaturated carboxylic acid of the present invention is characterized in that the method comprises a step of adding liquid to particles containing molybdenum, bismuth and iron and kneading the mixture, and extrusion-molding this kneaded substance, a step of preserving the molded article obtained by extrusion molding, and at least one step of drying and calcining the preserved molded article, and the contact time of particles containing molybdenum, bismuth and iron with liquid is 1 to 48 hours, and the preserving time of the molded article is 50% or more of the contact time of particles containing molybdenum, bismuth and iron with liquid. According to the production method of the present invention, catalytic activity can be easily controlled, and a catalyst having high activity and high selectivity is obtained.

TECHNICAL FIELD

The present invention relates to a method of producing an extrusionmolding catalyst containing at least molybdenum, bismuth and iron, usedin subjecting propylene, isobutylene, tert-butyl alcohol (hereinafter,referred to as TBA) or methyl tert-butyl ether (hereinafter, referred toas MTBE) to gas phase catalytic oxidation using molecular oxygen tosynthesize an unsaturated aldehyde and an unsaturated carboxylic acid.Further, the present invention relates to a catalyst produced by thismethod, and a method of synthesizing an unsaturated aldehyde and anunsaturated carboxylic acid using this catalyst.

BACKGROUND ART

Conventionally, there are a lot of suggestions on catalysts used insubjecting propylene, isobutylene, TBA or MTBE to gas phase catalyticoxidation to synthesize an unsaturated aldehyde and an unsaturatedcarboxylic acid, and on methods of producing the same.

The majority of such catalysts have a composition containing at leastmolybdenum, bismuth and iron, and industrially, a molding catalysthaving such a composition is used. The molding catalysts are classifiedinto extrusion molding catalysts, supporting molding catalysts and thelike depending on their molding methods. The extrusion molding catalystis produced usually via a process of kneading and extrusion-moldingparticles containing a catalyst component. On the other hand, thesupporting molding catalyst is produced usually via a process ofallowing a powder containing a catalyst component to be supported on asupport.

Regarding the extrusion molding catalyst, there are suggested, forexample, a method in which silica sol and inorganic fiber are added inproduction, for improvement of strength (Japanese Patent ApplicationLaid-Open (JP-A) No. 9-52053), a method in which a certain kind ofcellulose derivative is added in extrusion-molding a catalyst (JP-A No.7-16464), and the like. However, catalysts obtained by these knownmethods are not necessarily sufficient as industrial catalysts from thestandpoints of catalyst activity and selectivity of the intendedproduct, and the like, and there is desired further improvement.

Besides, the above-mentioned JP-A No. 9-52053 describes that a mixtureor kneaded substance of a catalyst component, silica sol and inorganicfiber is preserved by leaving it at room temperature for about 6 to 20hours under conditions not causing evaporation of moisture (preservingtreatment), before molding, to improve the mechanical strength of amolded catalyst. The reason for improvement in the strength of themolded body by preserving is described that by increase in the contacttime of a catalyst component with water and the like, the catalystcomponent is disintegrated into near primary particles, and a moldedarticle, when molded, becomes compact. However, preserving of a mixtureor kneaded substance having no definite shape is not necessarilyadvantageous, and control of activity is difficult in some cases.Further, sufficient selectivity of the intended product is notnecessarily obtained.

JP-A No. 2000-71313, Example 4 describes a method in which a clayeymaterial obtained by kneading an isobutylene oxidation catalystcontaining molybdenum, bismuth and iron is temporarily-molded into acylinder, which is filled in a cylinder of a piston type extrusionmolding machine, and extrusion-molded. However, in this method, atemporary-molded material in the form of cylinder and the final-moldedproduct are not preserved, therefore, activity of the resulted catalystmay be low in some cases.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a method of producing acatalyst for synthesis of an unsaturated aldehyde and unsaturatedcarboxylic acid, which can easily control catalytic activity and give acatalyst of high activity and high selectivity. Further, an object ofthe present invention is to provide a catalyst produced by this method,and a method of synthesizing an unsaturated aldehyde and unsaturatedcarboxylic acid at high yield using this catalyst.

The present invention relates to a method of producing an extrusionmolding catalyst containing at least molybdenum, bismuth and iron, usedin subjecting at least one of propylene, isobutylene, tert-butyl alcoholand methyl-tert-butyl ether to gas phase catalytic oxidation withmolecular oxygen to synthesize an unsaturated aldehyde and unsaturatedcarboxylic acid, wherein the method comprises the steps of

(i) adding liquid to particles containing molybdenum, bismuth and ironand kneading the mixture, and extrusion-molding this kneaded substance,

(ii) preserving the molded article obtained by extrusion molding, and

(iii) drying and/or calcining the preserved molded article,

and time from addition of liquid to particles containing molybdenum,bismuth and iron to immediately before the step (iii), namely contacttime of particles with liquid, is 1 to 48 hours, and

time of preserving the molded article in the step (ii), namelypreserving time, is 50% or more of the contact time of particlescontaining molybdenum, bismuth and iron with liquid.

Further, the present invention relates to a method of producing anextrusion molding catalyst containing at least molybdenum, bismuth andiron, used in subjecting at least one of propylene, isobutylene,tert-butyl alcohol and methyl-tert-butyl ether to gas phase catalyticoxidation with molecular oxygen to synthesize an unsaturated aldehydeand unsaturated carboxylic acid, wherein the method comprises the stepsof

(i) adding liquid to particles containing molybdenum, bismuth and ironand kneading the mixture, and molding, namely primary-molding, thiskneaded substance,

(ii) preserving the primary molded article obtained by molding,

(iii) extrusion-molding, namely secondary-molding, the primary moldedarticle preserved, and

(iv) drying and/or calcining the secondary molded article obtained byextrusion molding,

and time from addition of liquid to particles containing molybdenum,bismuth and iron to immediately before the step (iv), namely contacttime of particles with liquid, is 1 to 48 hours, and

time of preserving the primary molded article in the step (ii), namelypreserving time, is 50% or more of the contact time of particlescontaining molybdenum, bismuth and iron with liquid.

Furthermore, the present invention relates to the above-mentioned methodof producing a catalyst for synthesis of an unsaturated aldehyde andunsaturated carboxylic acid wherein, in the step of preserving themolded article or primary molded article, the preserving temperature is3 to 40° C.

Still further, the present invention relates to a catalyst for synthesisof an unsaturated aldehyde and unsaturated carboxylic acid, produced bythe above-mentioned method.

Even further, the present invention relates to a method of synthesizingan unsaturated aldehyde and unsaturated carboxylic acid wherein at leastone of propylene, isobutylene, tert-butyl alcohol and methyl-tert-butylether are subjected to gas phase catalytic oxidation with molecularoxygen in the presence of the above-mentioned catalyst.

The phrase “containing molybdenum, bismuth and iron” means “containingmolybdenum, bismuth and iron as metal elements”, and it is estimatedthat this metal element is contained in the form of oxide or complexoxide.

Hereinafter, the phrase “particles containing molybdenum, bismuth andiron” is substituted also by “particles containing catalyst components”.

BEST MODES FOR CARRYING OUT THE INVENTION

The catalyst obtained by the present invention contains at leastmolybdenum, bismuth and iron as catalyst components, and is used forsubjecting reaction raw materials propylene, isobutylene, TBA or MTBE togas phase catalytic oxidation with molecular oxygen to synthesize anunsaturated aldehyde and an unsaturated carboxylic acid. The reactionraw materials may be used singly or in combination of two or more ofthem.

Here, “unsaturated aldehyde and unsaturated carboxylic acid” meansspecifically acrolein or acrylic acid when the reaction raw material ispropylene, and methacrolein and methacrylic acid in the case of otherreaction raw materials. Depending on the catalyst composition andreaction conditions, either an unsaturated aldehyde or an unsaturatedcarboxylic acid is produced in some cases, and the present inventionincludes such cases.

The method of producing a catalyst for synthesizing an unsaturatedaldehyde and unsaturated carboxylic acid comprises, as described above,the steps of

(i) adding liquid to particles containing catalyst components andkneading the mixture, and extrusion-molding this kneaded substance,

(ii) preserving the molded article obtained by extrusion molding, and

(iii) drying and/or calcining the preserved molded article,

or the steps of

(i) adding liquid to particles containing catalyst components andkneading the mixture, and molding, namely primary-molding, this kneadedsubstance,

(ii) preserving the primary molded article obtained by molding,

(iii) extrusion-molding, namely secondary-molding, the primary moldedarticle preserved, and

(iv) at least one step of drying and calcining the secondary moldedarticle obtained by extrusion molding,

and controls the contact time of particles containing catalystcomponents with liquid from 1 to 48 hours by regulation of thepreserving time of the molded article (also including primary moldedarticle) and controls the preserving time of the molded article at 50%or more of the contact time of particles containing catalyst componentswith liquid. In the present invention, it is necessary that “preservingtime of the molded article” is more than time other than “preservingtime of the molded article” in “contact time of particles containingcatalyst components with liquid”, namely, more than the total time oftimes necessary for kneading and molding and the preserving time of akneaded substance having no definite shape.

By thus controlling the contact time of particles containing catalystcomponents with liquid by regulation of the preserving time of themolded article, the activity of the resulted catalyst can be easilycontrolled, and a catalyst having excellent activity and showingexcellent selectivity of the intended product can be obtained.Therefore, according to the present invention, a catalyst of highactivity and high selectivity having uniform activity is obtained, andby use of this catalyst, an unsaturated aldehyde and an unsaturatedcarboxylic acid can be produced in high yield.

Though the reason for a fact that a catalyst of high activity and highselectivity having uniform activity is obtained is not apparent, it issupposed that by conducting preserving after molding in constant form,elution and diffusion of molybdenum, bismuth, iron and other catalystcomponents, particularly, alkali metals such as potassium, cesium andthe like occur without localization during preserving, and these arerearranged without localization in the subsequent drying andcalcination.

In the present invention, it is important that kneaded substances areall molded in constant form. By molding kneaded substances all inconstant form, deviation of the activity of the resulted catalystfurther decreases and reproducibility also increases.

Here, “preserving” indicates leaving of a catalyst molded articlecontaining liquid before drying and calcination (also involving primarymolded article) under condition causing difficult evaporation of theliquid. As the preserving method, a method in which a catalyst moldedarticle (also including primary molded article) is wrapped by a plasticfilm, plastic sheet or the like, or placed in a closed vessel and leftunder condition suppressing evaporation of liquid, or other methods andthe like are mentioned. “contact time of particles containing catalystcomponents (particles containing molybdenum, bismuth and iron) withliquid” indicates time from addition of liquid to particles containingcatalyst components in kneading to immediately before a step of dryingand/or calcining a molded article (also including secondary moldedarticle). Further, here, “drying” indicates positive evaporation ofliquid contained in a molded article such as air drying and hot airdrying and the like. Calcination indicates heating treatment at hightemperature in common use.

The catalyst for synthesis of an unsaturated aldehyde and an unsaturatedcarboxylic acid and the method of producing the same, according to thepresent invention, will be illustrated in detail below.

The catalyst of the present invention is an extrusion-molded catalystcontaining as catalyst components at least molybdenum, bismuth and iron.As the catalyst component, in addition, silicon, cobalt, nickel,chromium, lead, manganese, calcium, magnesium, niobium, silver, barium,tin, tantalum, zinc, phosphorus, boron, sulfur, selenium, tellurium,cerium, tungsten, antimony, titanium, lithium, sodium, potassium,rubidium, cesium, thallium and the like may be contained. The catalyst(particles containing catalyst components) of the present invention isestimated as a complex oxide of molybdenum, bismuth, iron and othermetal elements.

Such an extrusion-molded catalyst containing at least molybdenum,bismuth and iron is produced generally via (1) a step of producingparticles containing catalyst components, (2) a step of kneading theresulted particles containing catalyst components, and the like, (3) astep of extrusion-molding the resulted kneaded substance, and (4) a stepof drying and/or calcining (heat treating) the resulted molded article.In the present invention, before drying and/or calcining the moldedarticle, namely, between the step (3) and the step (4), a step ofpreserving the molded article obtained by extrusion molding is furtherincluded. Further, in the present invention, it may also be permissiblethat molding, namely primary molding, is conducted once, and preservingis effected, then, molding, namely secondary molding, into the finalshape is conducted.

In the present invention, the step (1) is not particularly restricted,and conventionally known various methods can be applied, and usually, anaqueous slurry containing at least molybdenum, bismuth and iron isdried, and if necessary, further ground to give particles.

The method of producing an aqueous slurry containing at leastmolybdenum, bismuth and iron is not particularly restricted, andproviding there is no remarkable localization of components,conventionally well known various methods can be used such as aprecipitation method, oxide mixing method and the like.

As the raw material of the catalyst component to be dissolved in anaqueous slurry, oxides, sulfates, nitrates, carbonates, hydroxides,ammonium salts, halides and the like of various elements can be used.For example, as the molybdenum raw material, ammonium p-molybdate,molybdenum trioxide and the like are listed. The raw materials of thecatalyst components may be used singly or in combination of two or morefor each element.

The method of drying an aqueous slurry to give particles is notparticularly restricted, and there can be applied, for example, a methodof drying using a spray drier, a method of drying using a slurry drier,a method of drying using a drum drier, a method of drying to solid byevaporation and grinding the dried substance in the form of bulk, andother methods. Of them, it is preferable to obtain dry particles in theform of sphere using a spray drier, since particles are obtainedsimultaneously with drying and since the form of the resulted particleis a regular shape suitable for the present invention. Though the dryingconditions vary depending on the drying method, when a spray drier isused, the inlet temperature is usually from 100 to 500° C., the outlettemperature is usually 100° C. or more, preferably, from 105 to 200° C.

Thus obtained dry particles contain salts of nitric acid and the likederived from catalyst raw materials and the like in some cases, and whenthese salts are decomposed by calcination after molding, there is apossibility of decrease in the strength of a molded article. For thisreason, it is preferable that particles are not only dried, but alsocalcined in this stage to give calcined particles. The calcinationconditions are not particularly restricted, and known calcinationconditions can be applied. Usually, calcination is conducted in atemperature range of from 200 to 600° C., and the calcination time isappropriately selected depending on the intended catalyst.

The average particle diameter of dry particles or calcined particlescontaining catalyst components used for molding is preferably 10 μm ormore, further preferably 20 μm or more, particularly preferably 45 μm ormore. When the average particle diameter of particles containingcatalyst components increases, there is a tendency that a large void,namely, a large pore is formed between particles after molding, toincrease selectivity. The average particle diameter of dry particles orcalcined particles containing catalyst components used for molding ispreferably 150 μm or less, further preferably 100 μm or less,particularly preferably 65 μm or less. When the average particlediameter of particles containing catalyst components decreases, thenumber of contact points between particles per unit volume increases,therefore, there is a tendency of increase in the mechanical strength ofthe resulted catalyst molded article.

The bulk density of particles containing catalyst components ispreferably 0.5 kg/L or more, further preferably 0.8 kg/L or more, fromthe standpoint of handling. The bulk density of particles containingcatalyst components is preferably 1.8 kg/L or less, further preferably1.2 kg/L or less, from the standpoint of performance.

The strength of particles containing catalyst components is preferably9.8×10⁻⁴ N or more since when the strength is small, particles arebroken in molding, leading to little effective pore. On the other hand,the strength of particles containing catalyst components is preferably9.8×10⁻² N or less since when the strength is large, selectivitydecreases in some cases.

Next, in the step (2), a mixture of particles obtained in the step (1)and liquid is kneaded.

The apparatus used for kneading is not particularly restricted, and forexample, a batch-wise kneader using a double arm type stirring blade,continuous kneaders of axis rotation reciprocation mode, self cleaningmode and the like, can be used. Of them, batch-wise apparatuses arepreferable since kneading can be conducted while confirming thecondition of the kneaded substance. The termination of kneading isusually judged temporally, visually or by manual touch.

As the liquid used in the step (2), water and alcohols are preferable.As such alcohols, for example, lower alcohols such as ethanol, methylalcohol, propyl alcohol, butyl alcohol and the like are listed. Of them,water is particularly preferable from the standpoints of economy andhandling. These liquids may be used singly or in combination of two ormore.

The use amount of liquid is appropriately selected depending on the kindand size of particles, the kind of liquid, and the like, and usually, itis from 10 to 70 parts by weight based on 100 parts by weight ofparticles containing catalyst components obtained in the step (1). Theuse amount of liquid is preferably 20 parts by weight or more, furtherpreferably 30 parts by weight or more, particularly preferably 35 partsby weight or more based on 100 parts by weight of particles containingcatalyst components. When the use amount of liquid increases, there is atendency that a large void, namely, a large pore is formed in the driedand calcined molded article (extrusion-molded catalyst of the presentinvention) to increase selectivity. On the other hand, the use amount ofliquid is preferably 60 parts by weight or less, further preferably 50parts by weight or less, particularly preferably 45 parts by weight orless based on 100 parts by weight of particles containing catalystcomponents. When the use amount of liquid decreases, there is a tendencythat adhesion in molding lowers and handling increases, and the moldedarticle becomes more compact, leading to increase in the strength of themolded article.

In the step (2), further, it is preferable to add a molding auxiliarysuch as an organic binder and the like. By addition of a moldingauxiliary, the strength of the resulted molded article increases. Assuch a molding auxiliary, for example, methylcellulose, ethylcellulose,carboxymethylcellulose, carboxymethylcellulosesodium,hydroxyethylcellulose, hydroxypropylcellulose,hydroxypropylmethylcellulose, hydroxyethylmethylcellulose,hydroxybutylmethylcellulose, ethylhydroxyethylcellulose,hydroxypropylcellulose and the like are listed. These moldingauxiliaries may be used singly or in combination of two or more. It isusual that the addition amount of the molding auxiliary is preferably0.1 part by weight or more, particularly preferably 2 parts by weight ormore based on 100 parts by weight of particles containing catalystcomponents. Further, it is usual that the addition amount of the moldingauxiliary is preferably 10 parts by weight or less, particularlypreferably 6 parts by weight or less based on 100 parts by weight ofparticles containing catalyst components since then post treatments suchas heat treatment after molding and the like become easy.

Further, in the step (2), conventionally known additives other than theabove-mentioned auxiliaries may be used. As such additives, for example,inorganic compounds such as graphite, diatomaceous earth and the like,inorganic fibers such as glass fiber, ceramic fiber, carbon fiber andthe like, and so on are listed.

In the step (3), the kneaded substance obtained in the step (2) isextrusion-molded. Though this molding may be molding into the finalintended shape, primary molding is preferable from the standpoint ofproductivity.

As the primary molding method, for example, extrusion molding and pressmolding are listed. Of them, extrusion molding is preferable, and morepreferable is extrusion molding using a screw type extruder from thestandpoint of productivity. Further, the kneading step (2) and theextrusion molding step (3) may be carried out continuously, and they mayalso be conducted simultaneously using an integrated type apparatussuitable for this.

The form of the primary molded article is not particularly restricted,and for example, cylinder, rectangular parallelopiped, cube and the likeare selected. Also the size of the molded article is not particularlyrestricted, and size of certain level or more is preferable sincereproducibility tends to increase when the size is larger. For example,the size of the thinnest portion of the primary molded article ispreferably 10 mm or more, further preferably 30 mm or more.

In the present invention, after primary molding, the primary moldedarticle is preserved, and the contact time of particles containingcatalyst components with liquid is controlled. When preserving at thefinal intended form is possible, shaping into the final intended form isconducted without effecting the primary molding, then, the moldedarticle is preserved.

Preserving is conducted by wrapping a molded article with a plasticfilm, plastic sheet or the like and/or placing a molded article into aclosed vessel, and leaving it for given time at given temperature undercondition suppressing evaporation of liquid. Particularly, it ispreferable that a molded article is wrapped with a plastic film, plasticsheet or the like so as to produce no clearance, to realize sealing, andit is more preferable that thus sealed article is further place in aclosed vessel for sealing.

As described above, it is necessary that “preserving time of the moldedarticle” is more than time other than “preserving time of the moldedarticle” in “contact time of particles containing catalyst componentswith liquid”, namely, more than the total time of times necessary forkneading and molding and the preserving time of a kneaded substancehaving no definite shape. Namely, the ratio of “preserving time of themolded article” is 50% or more, preferably 70% or more, furtherpreferably 80% or more, particularly preferably 90% or more in “contacttime of particles containing catalyst components with liquid”.

In the present invention, the contact time of particles containingcatalyst components with liquid is from 1 to 48 hours. The contact timeof particles containing catalyst components with liquid is preferably 3hours or more, further preferably 8 hours or more, particularlypreferably 20 hours or more. When the contact time of particlescontaining catalyst components with liquid is longer, the resultedcatalyst tends to have higher activity and also improvedreproducibility. The contact time of particles containing catalystcomponents with liquid is preferably 36 hours or less, furtherpreferably 30 hours or less, particularly preferably 27 hours or less.When the contact time of particles containing catalyst components withliquid is shorter, the resulted catalyst tends to have improvedselectivity.

During this period, the preserving time of the molded article ispreferably 0.5 hours or more, further preferably 1 hour or more,particularly preferably 6 hours or more, more preferably 18 hours ormore. On the other hand, the preserving time of the molded article ispreferably 46 hours or less, further preferably 34 hours or less,particularly preferably 28 hours or less, more preferably 25 hours orless.

The preserving temperature is usually from 3 to 40° C. The preservingtemperature is preferably 10° C. or more, further preferably 15° C. ormore. When the preserving temperature is higher, the resulted catalysttends to have increased activity. The preserving temperature ispreferably 35° C. or less, further preferably 30° C. or less. When thepreserving temperature is lower, the molded article tends to showdecreased adhesion and improved handling.

Preserving is not necessarily required to be conducted at constanttemperature, and the preserving temperature may be changed in theabove-mentioned temperature range, and when conducted at constanttemperature, control of activity and the like is easy.

It becomes possible to control the activity of the resulted catalyst, byregulation of the contact time of particles containing catalystcomponents with liquid and the preserving time. The preserving time andtemperature of the molded article may be appropriately selecteddepending on the activity of a catalyst powder and the activity of theintended molded article.

When the primary molded article is preserved, molding, namely secondarymolding, into the final intended shape is effected after preserving.

The method of secondary molding is not particularly restricted, and forexample, it may be conducted using an auger type extrusion moldingmachine, piston type extrusion molding machine and the like.

The form of the secondary molded article is not particularly restricted,and molding into any shape such as ring, cylinder, star and the like ispossible. The present invention is suitable when the secondary moldedarticle is in the form of ring, particularly, ring having a diameter of15 mm or less. “Ring form” is alternatively called “hollow cylinderform”.

In the primary molding and secondary molding, namely final molding, itis preferable not to conduct vacuum deaeration so as not to decrease thepore volume of a catalyst.

Next, in the step (4), a catalyst molded article is dried and/orcalcined to give a catalyst, namely product.

The drying method is not particularly restricted, and generally knownmethods such as hot air drying, humidity drying, far infrared drying,micro wave drying and the like can be optionally used. The dryingcondition may be appropriately selected depending on the intended watercontent.

Though the dry molded article is usually calcined, when particles arecalcined in the step (1) and an organic binder and the like are notused, it is also possible to omit calcination. The calcinationconditions are not particularly restricted, and known calcinationconditions can be applied. Usually, calcination is conducted attemperatures in a temperature range of from 200 to 600° C., and thecalcination time is appropriately selected depending on the intendedcatalyst.

It may be also permissible that the drying step is omitted, andcalcination is only conducted.

The catalyst containing at least molybdenum, bismuth and iron producedin the present invention preferably has a composition of the followinggeneral formula (I).Mo_(a)Bi_(b)Fe_(c)M_(d)X_(e)Y_(f)Z_(g)Si_(h)O_(i)   (I)

In the formula (I), Mo, Bi, Fe, Si and O represent molybdenum, bismuth,iron, silicon and oxygen, respectively, and M represents at least oneelement selected from the group consisting of cobalt and nickel, Xrepresents at least one element selected from the group consisting ofchromium, lead, manganese, calcium, magnesium, niobium, silver, barium,tin, tantalum and zinc, Y represents at least one element selected fromthe group consisting of phosphorus, boron, sulfur, selenium, tellurium,cerium, tungsten, antimony and titanium, and Z represents at least oneelement selected from the group consisting of lithium, sodium,potassium, rubidium, cesium and thallium.

a, b, c, d, e, f, g, h and i represent atomic ratios of elements, andwhen a=12, then, b=0.01 to 3, c=0.01 to 5, d=1 to 12, e=0 to 8, f=0 to5, g=0.01 to 2, and h=0 to 20, and i represents an oxygen atomic rationecessary for satisfying the above-mentioned atomic valences ofcomponents.

In the present invention, conventionally known inorganic compounds suchas graphite, diatomaceous earth and the like, inorganic fibers such asglass fiber, ceramic fiber, carbon fiber and the like, and so on can beadded. Addition thereof may be conducted in kneading of the step (2).

Next, the method of synthesizing an unsaturated aldehyde and anunsaturated carboxylic acid of the present invention will beillustrated.

In the method of synthesizing an unsaturated aldehyde and an unsaturatedcarboxylic acid of the present invention, a raw material gas containingany one or more of reaction raw materials, propylene, isobutylene, TBAand MTBE, and molecular oxygen is subjected to gas phase catalyticoxidation in the presence of a catalyst produced by the method of thepresent invention.

The reaction is usually conducted in a fixed bed. One catalyst layer maybe used or two or more catalyst layers may be used.

In this case, in a reaction tube, a catalyst may be diluted with inertcarriers such as silica, alumina, silica-alumina, silicon carbide,titania, magnesia, ceramic ball, stainless steel and the like. Further,these inert carriers may be added also in the step (2), namely, inkneading.

The concentration of reaction raw materials, propylene, isobutylene, TBAand MTB, in a raw material gas can be varied in the wide range, andpreferably is from 1 to 20 vol %.

Though it is economical to use air as a molecular oxygen source, airenriched with oxygen, and the like may also be used, if necessary. Themolar ratio of reaction raw materials to oxygen in the raw material gas,namely volume ratio, is preferably in a range from 1:0.5 to 1:3.

It is preferable that the raw material gas contains water in addition toreaction raw materials and molecular oxygen, and it is preferable thatthe raw material gas is diluted with an inert gas such as nitrogen,carbon dioxide and the like. The concentration of water in the rawmaterial gas is preferably from 1 to 45 vol %.

The reaction pressure is preferably from normal pressure to severalhundred kPa. The reaction temperature is selected usually in a rangefrom 200 to 450° C., preferably from 250 to 400° C. The contact time ispreferably from 1.5 to 15 seconds.

EXAMPLES

The present invention will be specifically illustrated by the followingexamples and comparative examples.

Parts in the examples and comparative examples are by weight. Forkneading, a batch-wise kneader equipped with a double arm type stirringblade was used. Analysis of a raw material gas and a reaction gas wasconducted by gas chromatography. The catalyst composition was determinedfrom the use amounts of catalyst raw materials.

The reaction ratio of raw material olefins, TBA and MTBE (hereinafter,referred to as reactivity), the selectivity of an unsaturated aldehydeand an unsaturated carboxylic acid produced, and the total yield of theunsaturated aldehyde and unsaturated carboxylic acid, in the examplesand comparative examples, were calculated according to the followingformulae.Reactivity (%)=A/B×100Selectivity (%) of unsaturated aldehyde=C/A×100Selectivity (%) of unsaturated carboxylic acid=D/A×100Total yield (%)=(C+D)/B×100

Here, A represents the mol number of raw material olefins, TBA or MTBEreacted, B represents the mol number of raw material olefins, TBA orMTBE fed, C represents the mol number of an unsaturated aldehydeproduced, and D represents the mol number of an unsaturated carboxylicacid produced.

Example 1

To 1000 parts of pure water was added 500 parts of ammonium p-molybdate,12.4 parts of ammonium p-tungstate, 23.0 parts of cesium nitrate, 27.4parts of antimony trioxide and 33.0 parts of bismuth trioxide, and theywere stirred with heating (solution A). Separately, to 1000 parts ofpure water was added 209.8 parts of ferric nitrate, 75.5 parts of nickelnitrate, 453.3 parts of cobalt nitrate, 31.3 parts of lead nitrate and5.6 parts of 85% phosphoric acid, sequentially, and they were dissolved(solution B). The solution B was added to the solution A to give anaqueous slurry, then, this aqueous slurry was made into dry particles inthe form of sphere having an average particle size of 60 μm using aspray drier. The dry spherical particles were calcined at 300° C. for 1hour then at 510° C. for 3 hours, to give a catalyst calcined substance.Thus obtained catalyst calcined substance had an average particle sizeof 55 μm, a particle strength of 1.3×10⁻² N and a bulk density of 0.95kg/L.

To 500 parts of thus obtained catalyst calcined substance was added 15parts of methylcellulose, and these were dry-mixed. Into this was mixed180 parts of pure water, and these were mixed (kneaded) by a kneader togive a clayey substance, then, the kneaded substance having no definiteshape was extrusion-molded using a screw type extrusion molding machine,to obtain a primary molded article in the form of cylinder having adiameter of 45 mm and a length of 280 mm, namely primary molding. Inmolding, vacuum deaeration was not conducted.

Then, this primary molded article was sealed by wrapping with a plasticfilm so as not to allow evaporation of water, further, placed in aclosed vessel and preserved in a constant temperature chamber of 25° C.for 22 hours. After preserving, this primary molded article wasextrusion-molded using a piston type extrusion molding machine, toobtain a catalyst molded article in the form of ring having an outerdiameter of 5 mm, an inner diameter of 2 mm and a length of 5 mm, namelysecondary molding. In molding, vacuum deaeration was not conducted.

Next, the resulted catalyst molded article was dried using a 110° C. hotair drier, and calcined again at 400° C. for 3 hours, to give a finalcalcined article of the catalyst molded article. In this operation, thecontact time of particles containing catalyst components with water was24 hours.

The composition of elements other than oxygen in the resulted catalystmolded article is as described below.Mo₁₂W_(0.2)Bi_(0.6)Fe_(2.2)Sb_(0.8)Ni_(1.1)Co_(6.6)Pb_(0.4)P_(0.2)Cs_(0.5)

This catalyst molded article was filled in a stainless reaction tube,and reaction was conducted using a raw material gas containing 5% ofisobutylene, 12% of oxygen, 10% of water vapor and 73% of nitrogen (allvol %) under normal pressure at a reaction temperature of 340° C. for acontact time of 3.6 seconds. As a result of the reaction, the reactivityof isobutylene was 98.1%, the selectivity of methacrolein was 89.9%, andthe selectivity of methacrylic acid was 4.0%.

Example 2

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 1 except that the preserving time was 7 hoursand the contact time of particles containing catalyst components withwater was 8 hours. As a result of the reaction, the reactivity ofisobutylene was 97.2%, the selectivity of methacrolein was 90.0%, andthe selectivity of methacrylic acid was 4.0%.

Example 3

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 1 except that the temperature of the constanttemperature chamber was 35° C. As a result of the reaction, thereactivity of isobutylene was 98.2%, the selectivity of methacrolein was89.7%, and the selectivity of methacrylic acid was 3.8%.

Example 4

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 1 except that the temperature of the constanttemperature chamber was 5° C. As a result of the reaction, thereactivity of isobutylene was 97.6%, the selectivity of methacrolein was89.9%, and the selectivity of methacrylic acid was 4.0%.

Comparative Example 1

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 1 except that, without conducting the primarymolding, the kneaded substance having no definite shape was sealed bywrapping with a plastic film, further, placed in a closed vessel andpreserved for 22 hours in a constant temperature chamber at 25° C.,then, this kneaded substance was extrusion-molded using a piston typeextrusion molding machine, to obtain a catalyst molded article in theform of ring having an outer diameter of 5 mm, an inner diameter of 2 mmand a length of 5 mm. In this operation, the contact time of particlescontaining catalyst components with water was 24 hours. As a result ofthe reaction, the reactivity of isobutylene was 97.6%, the selectivityof methacrolein was 89.4%, and the selectivity of methacrylic acid was3.3%.

In comparison with Examples 1 to 4, irregularity in activity among theproduced catalyst molded articles increased.

Comparative Example 2

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 1 except that preserving of the primary moldedarticle was not conducted. In this operation, the contact time ofparticles containing catalyst components with water was 40 minutes. As aresult of the reaction, the reactivity of isobutylene was 97.2%, theselectivity of methacrolein was 89.6%, and the selectivity ofmethacrylic acid was 3.5%.

In comparison with Examples 1 to 4, irregularity in activity among theproduced catalyst molded articles increased.

The results of Examples 1 to 4, and comparative Examples 1, 2 aresummarized in Table 1.

TABLE 1 Preserving Ratio of Reaction result preserving time CarboxylicPreserving Preserving of Contact time Aldehyde acid Timing oftemperature time molded article with liquid Reactivity selectivityselectivity Total yield preserving (° C.) (h) (%) (h) (%) (%) (%) (%)Example 1 Primary 25 22 91.7 24 98.1 89.9 4.0 92.1 molded articleExample 2 Primary ditto 7 85.7 8 97.2 90.0 4.0 91.4 molded articleExample 3 Primary 35 22 91.7 24 98.2 89.7 3.8 91.8 molded articleExample 4 Primary 5 22 91.7 24 97.6 89.9 4.0 91.6 molded articleComparative Kneaded 25 22 91.7 24 97.6 89.4 3.3 90.5 Example 1 substanceComparative — — 0 — 40 min. 97.2 89.5 3.5 90.4 Example 2

Example 5

To 1000 parts of pure water was added 500 parts by ammonium p-molybdate,6.2 parts of ammonium p-tungstate and 23.0 parts of cesium nitrate, andthey were stirred with heating (solution A). Separately, to 600 parts ofpure water was added 41.9 parts of 60 wt % nitric acid, and the mixturewas made uniform, then, 68.7 parts of bismuth nitrate was added anddissolved. To this was added 200.2 parts of ferric nitrate, 116.6 partsof nickel nitrate, 432.7 parts of cobalt nitrate and 54.5 parts ofmagnesium nitrate, sequentially, further, 400 parts of water was addedand they were dissolved (solution B). The solution B was added to thesolution A to give an aqueous slurry, then, 24.1 parts of antimonytrioxide was added and the mixture was stirred with heating, and driedusing a spray drier to give dry particles in the form of sphere havingan average particle size of 55 μm. The dry spherical particles werecalcined at 300° C. for 1 hour then at 510° C. for 3 hours, to give acatalyst calcined substance. Thus obtained catalyst calcined substancehad an average particle size of 51 μm, a particle strength of 1.7×10⁻² Nand a bulk density of 0.96 kg/L.

To 500 parts of thus obtained catalyst calcined substance was added 15parts of hydroxypropylmethylcellulose, and these were dry-mixed. Intothis was mixed 170 parts of pure water, and these were mixed (kneaded)by a kneader to give a clayey substance, then, the kneaded substancehaving no definite shape was extrusion-molded using a screw typeextrusion molding machine, to obtain a primary molded article in theform of cylinder having a diameter of 45 mm and a length of 280 mm,namely primary molding. In molding, vacuum deaeration was not conducted.

Then, this primary molded article was sealed by wrapping with a plasticfilm so as not to allow evaporation of water, further, placed in aclosed vessel and preserved in a constant temperature chamber of 25° C.for 22 hours. After preserving, this primary molded article wasextrusion-molded using a piston type extrusion molding machine, toobtain a catalyst molded article in the form of ring having an outerdiameter of 5 mm, an inner diameter of 2 mm and a length of 5 mm, namelysecondary molding. In molding, vacuum deaeration was not conducted.

Next, the resulted catalyst molded article was dried using a 110° C. hotair drier, and calcined again at 400° C. for 3 hours, to give a finalcalcined article of the catalyst molded article. In this operation, thecontact time of particles containing catalyst components with water was24 hours.

The composition of elements other than oxygen in the resulted catalystmolded article is as described below.Mo₁₂W_(0.1)Bi_(0.6)Fe_(2.1)Sb_(0.7)Ni_(1.7)Co_(6.3)Mg_(0.9)Cs_(0.5)

This catalyst molded article was filled in a stainless reaction tube,and reaction was conducted using a raw material gas containing 5% ofTBA, 12% of oxygen, 10% of water vapor and 73% of nitrogen (all vol %)under normal pressure at a reaction temperature of 340° C. for a contacttime of 3.6 seconds. As a result of the reaction, the reactivity of TBAwas 100%, the selectivity of methacrolein was 88.3%, and the selectivityof methacrylic acid was 2.5%.

Example 6

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 5 except that the preserving time was 1 hourand 15 minutes. In this operation, the contact time of particlescontaining catalyst components with water was 2 hours. As a result ofthe reaction, the reactivity of TBA was 100%, the selectivity ofmethacrolein was 88.1%, and the selectivity of methacrylic acid was2.3%.

Comparative Example 3

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 5 except that, without conducting the primarymolding, the kneaded substance having no definite shape was sealed bywrapping with a plastic film, further, placed in a closed vessel andpreserved for 22 hours in a constant temperature chamber at 25° C.,then, this kneaded substance was extrusion-molded using a piston typeextrusion molding machine, to obtain a catalyst molded article in theform of ring having an outer diameter of 5 mm, an inner diameter of 2 mmand a length of 5 mm. In this operation, the contact time of particlescontaining catalyst components with water was 24 hours. As a result ofthe reaction, the reactivity of TBA was 100%, the selectivity ofmethacrolein was 87.5%, and the selectivity of methacrylic acid was2.1%.

In comparison with Examples 5, 6, irregularity in activity among theproduced catalyst molded articles increased.

The results of Examples 5 and 6 and comparative Example 3 are summarizedin Table 2.

TABLE 2 Preserving Ratio of Reaction result preserving time CarboxylicPreserving Preserving of Contact time Aldehyde acid Timing oftemperature time molded article with liquid Reactivity selectivityselectivity Total yield preserving (° C.) (h) (%) (h) (%) (%) (%) (%)Example 5 Primary 25 22 91.7 24 100.0 88.3 2.5 90.8 molded articleExample 6 Primary 25 1 h 62.5  2 100.0 88.1 2.3 90.4 molded article 15min. Comparative Kneaded 25 22 — 24 100.0 87.5 2.1 89.6 Example 3substance

Example 7

To 1000 parts of pure water was added 500 parts by ammonium p-molybdate,6.2 parts of ammonium p-tungstate, 1.4 parts of potassium nitrate, 27.5parts of antimony trioxide and 49.5 parts of bismuth trioxide, and theywere stirred with heating (solution A). Separately, to 1000 parts ofpure water was added 123.9 parts of ferric nitrate, 288.4 parts ofcobalt nitrate and 28.1 parts of zinc nitrate, sequentially, and theywere dissolved (solution B). The solution B was added to the solution Ato give an aqueous slurry, then, this aqueous slurry was dried using aspray drier to give dry particles in the form of sphere having anaverage particle size of 60 μm. The dry spherical particles werecalcined at 300° C. for 1 hour, to give a catalyst calcined substance.Thus obtained catalyst calcined substance had an average particle sizeof 54 μm, a particle strength of 1.1×10⁻² N and a bulk density of 0.90kg/L.

To 500 parts of thus obtained catalyst calcined substance was added 15parts of methylcellulose, and these were dry-mixed. Into this was mixed185 parts of pure water, and these were mixed (kneaded) by a kneader togive a clayey substance, then, the kneaded substance having no definiteshape was molded using a screw type extrusion molding machine and a pillmachine, to obtain a primary molded article in the form of sphere havinga diameter of 20 mm, namely primary molding. In molding, vacuumdeaeration was not conducted.

Then, this primary molded article was sealed by wrapping with a plasticfilm so as not to allow evaporation of water, further, placed in aclosed vessel and preserved in a constant temperature chamber of 18° C.for 28 hours. After preserving, this primary molded article wasextrusion-molded using a screw type extrusion molding machine, to obtaina catalyst molded article in the form of ring having an outer diameterof 5 mm, an inner diameter of 2 mm and a length of 5 mm, namelysecondary molding. In molding, vacuum deaeration was not conducted.

Next, the resulted catalyst molded article was dried using a 110° C. hotair drier, and calcined again at 510° C. for 3 hours, to give a finalcalcined article of the catalyst molded article. In this operation, thecontact time of particles containing catalyst components with water was30 hours.

The composition of elements other than oxygen in the resulted catalystmolded article is as described below.Mo₁₂W_(0.1)Bi_(0.9)Fe_(1.3)Sb_(0.8)Co_(4.2)Zn_(0.4)K_(0.06)

This catalyst molded article was filled in a stainless reaction tube,and reaction was conducted using a raw material gas containing 5% ofpropylene, 12% of oxygen, 10% of water vapor and 73% of nitrogen (allvol %) under normal pressure at a reaction temperature of 310° C. for acontact time of 3.6 seconds. As a result of the reaction, the reactivityof propylene was 99.0%, the selectivity of acrolein was 91.0%, and theselectivity of acrylic acid was 6.5%.

Example 8

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 7 except that the kneaded substance having nodefinite shape was extrusion-molded using a screw type extrusion moldingmachine, to obtain a catalyst molded article in the form of ring havingan outer diameter of 5 mm, an inner diameter of 2 mm and a length of 5mm, and this molded article was sealed by wrapping with a plastic film,further, placed in a closed vessel and preserved for 28 hours in aconstant temperature chamber at 28° C. In this operation, the contacttime of particles containing catalyst components with water was 30hours. As a result of the reaction, the reactivity of propylene was99.0%, the selectivity of acrolein was 90.8%, and the selectivity ofacrylic acid was 6.4%.

Example 9

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 7 except that, before primary molding, thekneaded substance having no definite shape was sealed by wrapping with aplastic film, further, placed in a closed vessel and preserved for 12hours in a constant temperature chamber at 18° C., and the primarymolded article was sealed by wrapping with a plastic film and preservedfor 16 hours in a constant temperature chamber at 18° C. In thisoperation, the contact time of particles containing catalyst componentswith water was 30 hours. As a result of the reaction, the reactivity ofpropylene was 98.8%, the selectivity of acrolein was 90.7%, and theselectivity of acrylic acid was 6.4%.

Comparative Example 4

A catalyst molded article was produced and reaction was conducted in thesame manner as in Example 7 except that, without conducting the primarymolding, the kneaded substance having no definite shape was sealed bywrapping with a plastic film, further, placed in a closed vessel andpreserved for 28 hours in a constant temperature chamber at 18° C.,then, this kneaded substance was extrusion-molded using a piston typeextrusion molding machine, to obtain a catalyst molded article in theform of ring having an outer diameter of 5 mm, an inner diameter of 2 mmand a length of 5 mm. In this operation, the contact time of particlescontaining catalyst components with water was 30 hours. As a result ofthe reaction, the reactivity of propylene was 98.8%, the selectivity ofacrolein was 90.1%, and the selectivity of acrylic acid was 6.0%.

In comparison with Examples 7 to 9, irregularity in activity among theproduced catalyst molded articles increased.

The results of Examples 7 to 9 and Comparative Example 4 are summarizedin Table 3.

TABLE 3 Preserving Ratio of Reaction result preserving time CarboxylicPreserving of Contact time Aldehyde acid Timing of temperaturePreserving time molded article with liquid Reactivity selectivityselectivity Total yield preserving (° C.) (h) (%) (h) (%) (%) (%) (%)Example 7 Primary molded article 18 28 86.7 30 99.0 91.0 6.5 96.5Example 8 Final molded article 18 28 86.7 30 99.0 90.8 6.4 96.2 Example9 Kneaded substance 18 12 + 16 53.3 30 98.8 90.7 6.4 95.9 Primary moldedarticle Comparative Kneaded substance 18 28 — 30 98.8 90.1 6.0 94.9Example 4

INDUSTRIAL APPLICABILITY

The catalyst for synthesis of an unsaturated aldehyde and an unsaturatedcarboxylic acid which is obtained by the present invention is excellentin catalytic activity and in selectivity of the intended product.Therefore, by using this catalyst, an unsaturated aldehyde and anunsaturated carboxylic acid can be produced with good yield. Further,according to the method of producing a catalyst for synthesis of anunsaturated aldehyde and an unsaturated carboxylic acid of the presentinvention, catalytic activity can be easily controlled.

1. A method of producing an extrusion molding catalyst comprisingmolybdenum, bismuth and iron, used for the catalytic gas phase oxidationof at least one of propylene, isobutylene, tert-butyl alcohol andmethyl-tert-butylether with molecular oxygen, to form at least one of anunsaturated aldehyde and an unsaturated carboxylic acid, the methodcomprising: drying an aqueous slurry containing molybdenum, bismuth andiron to form dried particles in the form of a sphere; calcining thedried particles at a temperature of from 200 to 600° C. to form calcinedparticles; adding a liquid to the calcined particles comprisingmolybdenum, bismuth and iron, to form a first mixture; kneading thefirst mixture to form a kneaded mixture; carrying out a primary moldingof the kneaded mixture to form a molded article, wherein the primarymolding is extrusion molding; preserving the molded article for apreserving time; extrusion molding the molded article to form anextrusion molded article; and drying, calcining or both drying andcalcining the extrusion molded article; wherein the time from adding theliquid to the calcined particles to immediately before the drying, thecalcining or the both drying and the calcining of the preserved moldedarticle is from 1 to 48 hours, and wherein the preserving time is aperiod of time that is 50% or more of the period of time which theparticles are in contact with the liquid.
 2. The method according toclaim 1, wherein the preserving is carried out at a temperature of from3 to 40° C.
 3. The method according to claim 1, wherein the liquid iswater.
 4. The method according to claim 1, wherein from 10-70 parts byweight of liquid are added to the particles, wherein parts by weight isbased on 100 parts by weight of the particles.
 5. A catalyst produced bythe method of claim
 1. 6. The method according to claim 1, wherein thecalcining decomposes a nitrate present in the dried particles.
 7. Acatalyst produced by the method of claim
 2. 8. A catalyst produced bythe method of claim
 3. 9. A catalyst produced by the method of claim 4.